111 lines
2.9 KiB
C++
111 lines
2.9 KiB
C++
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// -- Boost Lambda Library -------------------------------------------------
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// Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// For more information, see www.boost.org
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// --------------------------------------------------
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#ifndef BOOST_LAMBDA_ARITY_CODE_HPP
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#define BOOST_LAMBDA_ARITY_CODE_HPP
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#include "boost/type_traits/cv_traits.hpp"
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#include "boost/type_traits/transform_traits.hpp"
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namespace boost {
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namespace lambda {
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// These constants state, whether a lambda_functor instantiation results from
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// an expression which contains no placeholders (NONE),
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// only free1 placeholders (FIRST),
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// free2 placeholders and maybe free1 placeholders (SECOND),
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// free3 and maybe free1 and free2 placeholders (THIRD),
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// freeE placeholders and maybe free1 and free2 (EXCEPTION).
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// RETHROW means, that a rethrow expression is used somewhere in the lambda_functor.
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enum { NONE = 0x00, // Notice we are using bits as flags here.
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FIRST = 0x01,
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SECOND = 0x02,
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THIRD = 0x04,
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EXCEPTION = 0x08,
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RETHROW = 0x10};
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template<class T>
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struct get_tuple_arity;
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namespace detail {
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template <class T> struct get_arity_;
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} // end detail;
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template <class T> struct get_arity {
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BOOST_STATIC_CONSTANT(int, value = detail::get_arity_<typename boost::remove_cv<typename boost::remove_reference<T>::type>::type>::value);
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};
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namespace detail {
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template<class T>
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struct get_arity_ {
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BOOST_STATIC_CONSTANT(int, value = 0);
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};
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template<class T>
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struct get_arity_<lambda_functor<T> > {
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BOOST_STATIC_CONSTANT(int, value = get_arity<T>::value);
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};
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template<class Action, class Args>
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struct get_arity_<lambda_functor_base<Action, Args> > {
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BOOST_STATIC_CONSTANT(int, value = get_tuple_arity<Args>::value);
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};
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template<int I>
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struct get_arity_<placeholder<I> > {
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BOOST_STATIC_CONSTANT(int, value = I);
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};
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} // detail
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template<class T>
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struct get_tuple_arity {
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BOOST_STATIC_CONSTANT(int, value = get_arity<typename T::head_type>::value | get_tuple_arity<typename T::tail_type>::value);
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};
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template<>
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struct get_tuple_arity<null_type> {
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BOOST_STATIC_CONSTANT(int, value = 0);
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};
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// Does T have placeholder<I> as it's subexpression?
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template<class T, int I>
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struct has_placeholder {
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BOOST_STATIC_CONSTANT(bool, value = (get_arity<T>::value & I) != 0);
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};
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template<int I, int J>
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struct includes_placeholder {
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BOOST_STATIC_CONSTANT(bool, value = (J & I) != 0);
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};
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template<int I, int J>
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struct lacks_placeholder {
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BOOST_STATIC_CONSTANT(bool, value = ((J & I) == 0));
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};
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} // namespace lambda
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} // namespace boost
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#endif
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